Method and apparatus for tensioning a moving strip



M. H. BURSK Aug. 5, 1W9

METHOD AND APPARATUS FOR TENSIONING A MOVING STRIP Filed Sept, 26. 19676 Sheets-Sheet '1 INVENTOR. MAX H. 5095K Y W,M

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METHOD AND APPARATUS FOR TBNSIONING A MOVING STRIP Filed Sept. 26. 1967M. H. BURSK Aug. 5, 1969 6 Sheets-Sheet 2 Il'nmullllhm a m 2 @m m 1 A Mn3 W I'lIlIIlII" S- 1959 r M. H. BURSK 3,459,135!

METHOD AND APPARATUS FOR TENSIONING A MOVING STRIP F'iIe d Se t. 26.19s? s Sheets-Sheet 3 N v Q N v INVENTOR. Q Q MAX H. 50am T j BY K, i

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Allg- 5, 1969 M. H. BURSK 3,459,851

METHOD AND APPARATUS FOR TENSIONING A MOVING STRIP Filed Sept. 26, 1967I, s Sheets-Sheet 4 fi/ 103 ll l 105- E; T- J /06 i n I 7/ 60 L 95 l a!if 77 76 Z 5 76 v w 32 Z 3 H ll INVENTOR.

un; H MAX A. 50mm I1 I BYZ a l l u w A m 6 Sheets-Sheet 5 M. H. BURSKMETHOD AND APPARATUS FOR TENSIONING A MOVING STRIP Aug. 5, 1969INVENTOR. M X A! 019.57?

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ATTORNEYS.

' Filedse pt. 26. 1967 United States Patent- 3,459,351 METHOD ANDAPPARATUS FOR TENSIONING A MOVING STRIP Max H. Bursk, North Olmsted,Ohio, assignor to Wilson Lee Engineering Company, Inc., Cleveland, Ohio,a corporation of Ohio Filed Sept. 26, 1967, Ser. No. 670,707 Int. Cl.B65h 23/18, 23/08 US. Cl. 226-39 14 Claims ABSTRACT OF THE DISCLOSURE Amethod and apparatus for applying a pulling or tensioning force to amoving strip or web, such as sheet steel for example, either in thedirection of travel of the strip or opposite to the direction of travel.A vacuum system is used in cooperation with moving belts to apply thetensioning force.

Background of the invention The handling of elongated strip materialduring processing requires special consideration when the strip isinitially stored in coil form. The coils of strip material, such as websof sheet steel, nonferrous metals, paper, plastic film, cloth and thelike, are often wound on reels or mandrels between processing operationsand the strip is fed into a processing line by means of pinch rolls,conveyors, or the like after which it is recoiled for further handling.Control of the strip as it translates through the processing line isfrequently best accomplished by keeping the strip under tension from thepay-off reel to the winding reel.

In many applications it has been difficult to keep the strip under thedesired tension due to such problems as the feeding out of free loops ofthe strip where transient variations in the speed of translation occurand the paying off or feeding of the strip from a free position or aloose or open coil. One such situation, where annealed steel strip mustbe fed from an open coil in the vertical on edge position to a flathorizontal condition for feeding through a temper mill, requires thatthe strip be twisted 90 between the open coil and the temper mill. Inthese and other applications it is both necessary and advantageous tohave the strip under tension to help guide the strip and to providedesired back tension.

Existing apparatus generally employs bridle rolls or pinch rolls todevelop the back tension. Bridle rolls require that the strip be passedaround one roll for at least 180 and then passed around another parallelroll with a reverse bend for at least 180 with resulting danger of coilbreaks. Pinch rolls, it effective as a tension creating means, may alsochange the physical condition of the strip in an undesired manner.

The method and apparatus of the present invention overcome thedifficulties indicated above and afford other features and advantagesnot obtainable from the prior art.

Summary of the invention It is among the objects of the invention todevelop tension in a moving strip being fed to or removed from aprocessing unit.

Another object of the invention is to synchronize the speed of a movingstrip so that there is no relative movement between the strip and thoseparts of the tensioning apparatus which convey the strip to or from theprocessing unit.

Patented Aug. 5, 1969 These and other objects are accomplished through amethod and apparatus including, as a part of the apparatus, an endlessmain belt driven in a path of travel which includes an elongated spanparallel to the direction of travel of the strip, the belt portionmoving across the span being adapted to engage the adjacent surface ofthe moving strip. The main belt has spaced transverse grooves formed inthe outer surface thereof which extend intermediate the side edges ofthe belt and may extend beyond the side edges of the strip moving acrossthe span, depending upon the width of the strip being handled. The mainbelt also has openings formed therein which are spaced longitudinallyaround its perimeter and which are located in the grooves. Cooperatingwith the main belt are one or more endless sealing belts adapted forlocation with a moving portion thereof adjacent and in simultaneousparallel motion with the portion of the main belt moving across thespan, the sealing belt being adapted to seal the transverse grooves inthe portion of the main belt between the edges of the moving strip andthe sides of the strip engaging span of the main belt. A vacuum systemis provided contiguously with the portion of the main belt which extendsacross the span and is adapted to communicate with openings through thebelt for evacuating atmosphere from the transverse grooves therein whilethe belt is in motion. The strip tensioning force is applied to the mainbelt by means of a suitable dynamoelectric device or the like.

The apparatus may include a mechanism for pivoting the endless sealingbelt into and out of sealing engagement with the span of the main beltwhile the strip is moved along with the span portion of the main belt.

According to one form of the invention two endless sealing belts areutilized, one located on each side of the main belt in a fashion wherebythe two sealing belts seal the opposite ends of the transverse groovesbetween the sides of the main belt and the edges of the strip.

According to another aspect of the invention a mechanism is provided fordetecting a variation between the speed of the strip passing through theapparatus and the surface speed of one of the belts in the span (i.e.,slippage) and for using this variation, if detected, for adjusting thetensioning force exerted by the belts on the strip to reduce theslippage.

Other objects, uses and advantages will be apparent from the followingdetailed description and drawings which illustrate a preferred form ofthe invention and wherein like parts are indicated by like numerals.

Brief description of the drawings FIGURE 1 is a side elevational view ofthe apparatus embodying the invention and indicating in dash lines theupward limit of the angular adjustment thereof. Also shown in dot anddash lines is the position of the sealing belt unit when the apparatusis open to receive or thread a strip therethrough;

FIGURES 2 and 2A show a plan view of the apparatus of FIGURE 1, FIGURE2A being an extension of FIG- URE 2 on the right hand side thereof, withparts broken away for the purpose of illustration;

FIGURE 3 is an end elevational view of the apparatus of FIGURE 1;

FIGURE 4 is a fragmentary end elevational view similar to FIGURE 3 withparts broken away and shown in section;

FIGURE 5 is a fragmentary sectional view taken on the line 5-5 of FIGURE1;

FIGURE 6 is a fragmentary sectional view on an enlarged scale taken onthe line 6--6 of FIGURE 1;

FIGURE 7 is a fragmentary elevational view on an enlarged scaleillustrating the drive mechanism for the upper sealing belts, takensubstantially on line 77 of FIG- URE 3;

FIGURE 8 is a fragmentary sectional view on an enlarged scale taken onthe line 8-8 of FIGURE 2; and

FIGURE 9 is a fragmentary sectional view on an enlarged scale taken onthe line 9-9 of FIGURE 2.

Description of the illustrated embodiment Referring more particularly tothe drawings there is shown a tensioning apparatus A embodying theinvention and adapted to exert a tensioning force on a strip B of sheetsteel being supplied from a coil C as best shown in FIGURES 1, 2 and 3.The apparatus includes a base 10 and a table 11 mounted for horizontalmovement on the base 10 about a vertical pivot pin 12 and resting onbearing plates 13, 14, 15 and 16. A hydraulic cylinder 18 located at thefar right-hand end of the base 10 and table 11 as viewed in FIGURE 2serves to pivot the table 11 in a horizontal plane about the pivot pin12 and locate the apparatus at a desired angular disposition forreceiving the strip B from the coil C, the cylinder 18 being pivotallyconnected at one end to a bracket 19 mounted on the frame 10 and thepiston rod 18 extending from its other end and being pivotally connectedto a bracket 20 mounted on the table 11.

Mounted in pillow blocks 21 and 22 on the table 11 is a shaft 23 whichis connected to a reduction unit in a gear box 24 through a coupling 25.The reduction unit in the gear box 24 is connected to a dynamoelectricmachine 26 through a flexible coupling 27. The machine 26 may be eithera drive motor for rotating shaft 23 when the apparatus is used to exerta moving force on the stri or an electrical brake means when theapparatus is used to exert a hold-back or retarding tension on stripbeing advanced by other means. It will be understood that differentmeans for developing tension or drag on the strip may also be used, suchfor example as a fluid operated slip brake, an eddy current clutch or ahydraulic pump acting against a hydraulic relief valve.

Pivotably mounted on hearing sleeves 30 and 31 on the shaft 23 are sideframe members 32 and 33 (see FIG- URE 4) which may be moved about theaxis of the shaft 23 to the desired tilt angle between the horizontalposition shown in solid lines in FIGURE 1 and the upwardly tiltedposition shown in dash lines. The position of the members 32 and 33 isadjusted by means of hydraulic cylinders 34 and 35 pivotally connectedat one end to the frame members 32 and 33 respectively and at theirother ends to the table 11 as best shown in FIGURES 1, 3 and 6.

Keyed to the shaft 23 (FIGURE 4) is a head pulley 36 which drives a mainbelt 37 extending between the head pulley 36 and a tail pulley 38carried by an idler shaft 39 mounted in bearing blocks 40 and 41 securedto the frame members 32 and 33 respectively.

The upwardly facing portion of the main belt 37 defines an elongatedspan extending between the head pulley 36 and tail pulley 38 and isadapted to support the strip B during its travel across the span. Thebelt portion moving across the span is adapted frictionally to engagethe adjacent under-surface of the moving strip B and is supported frombelow by a series of transverse idler rollers 44 journaled at their endsin the frame members 32 and 33.

Suitable tension is maintained in the main belt 37 by means of a tensionroller 46 (FIGURES 1 and 5) journaled in opposite arms of a yoke member47 which is slidably received in a transverse member 48, U-shaped incross-section, which extends between and is secured at its end to theframe members 32 and 33 (see FIGURES 1 and 5 Tension is applied to themain belt 37 by means of a hydraulic cylinder 49 mounted on thetransverse member 47.

Formed on the inner surface of the main belt 37 are two longitudinalparallel ribs 50 and 51 which are received in matching annular grooves52 and 53 in the head pulley 36 as well as annular grooves 55 and 56 inthe tail pulley 38 and grooves 57 and 58 in the idler rolls 44 (FIGURES2 and 8). Formed in the outer face of the main belt 37, and uniformlyspaced apart along its entire length, are spaced transverse grooves 60which extend intermediate its side edges (FIGURE 2) and serve a purposeto be described in detail below.

Extending longitudinally across the span of the main belt 37 between thehead pulley 36 and tail pulley 38 is an elongated vaGuum box 61 fromwhich atmosphere is evacuated by means of a pump 62, the box 61 havingopenings 63 formed in the upwardly facing side thereof (FIGURES l and8). Secured to the top of the vacuum box 61 is a belt engaging slab 64,preferably formed of a relatively soft nonabrasive material such aswood, which has openings 65 formed therein to match the openings 63.Extending along the top of the slab 64 are longitudinal slots 66 locatedalong the lines defined by the rows of openings 65.

Formed in the lateral grooves 60 of the main belt 37 are openings 70arranged in two parallel longitudinal rows around the periphery of thebelt and located over the slots 66 in the stab 64 when the main beltpasses across the span between the pulleys 36 and 38. Accordingly, thevacuum produced in the vacuum box 61 is effective in the lateral grooves60 in the main belt 37 as they pass over the vacuum box 61 to provideeffective frictional engagement between the main belt and the strip B asthey travel across the span.

Pivotally connected to the side frame members 32 and 33 are two upperframe members 70 and 71. Mounted below the rearward (to the left inFIGURE 1) end portions of the upper frame members 70 and 71 are bearingplates 72 and 73 which are rotatably mounted on bearing sleeves 74 and75 secured to the main frame members 32 and 33 (FIGURES 3 and 9). Theside frame members 70 and 71 are pivotally supported on the bearingsleeves 74 and 75 relative to the main frame members 32 and 33 and aremovable between a closed position shown in dash lines and an openposition shown in dot and dash lines in FIGURE 1 by means of hydrauliccylinders 76 and 77. The cylinders 76 and 77 are pivotally mounted inthe main frame members 32 and 33 respectively (FIGURE 6) by means ofbinge pins 78 and 79 and the pistons thereof are pivotally connected tothe members 70 and 71 respectively by means of hinge pins 80 and 81.Rotatably mounted between the rearward ends of upper frame members 70and 71 on a transverse shaft 84 are sealing belt head pulleys 85 and 86(FIGURES 2, 3 and 4). Mounted at the opposite ends of the frame members70 and 71 are sealing belt tail pulleys 87 and 88 mounted on a shaft 89journaled in bearing brackets 91 and 92 on the members 70 and 71.

Sealing belts 93 and 94 are looped around the cooperating head and tailpulleys 85 and 87, and 86 and 88 respectively with their bottom reachesdisposed directly above and adapted for simultaneous parallel motionwith the top reach of the main belt 37 as it moves across the spanbetween the pulleys 36 and 38. The sealing belts 93 and 94 engage theouter side portions of the main belt 37 and overlie the ends of thelateral grooves 60 as well as the marginal edge portions of the strip Blocated between the main belt 37 and the sealing belts 93 and 94. Thusthe sealing belts 93 and 94 serve to seal the lateral grooves 60 betweenthe edges of the strip B and the side portions of the belt 37 andprevent the entry of atmosphere into grooves 60 even though the width ofstrip being handled may vary as will be explained later.

Accordingly atmospheric pressure is effective, due to the vacuum appliedto the grooves 60, to press the strip B into firm frictional engagementwith the main belt 37 and also to press the sealing belts 93 and 94 intofrictional engagement with the marginal portions of the top surface ofthe strip B.

Tension in the belts 93 and 94 is maintained by means of tension rollers95 and 96 which depress the belts 93 and 94 between the head pulleys 85and 86 and idler rolls 97 and 98 (FIGURE 1). The belts 93 and 94 havecentral longitudinal ribs 99 and 100 respectively, which are received incorresponding annular grooves 85 and 86' formed in the head pulleys 85and 86 respectively as well as corresponding grooves formed in the tailpulleys 87 and 88, tension rollers 95 and 96, and idler rolls 97 and 98.The tension rollers 95 and 96 are operated by means of hydrauliccylinders 101 and 102 respectively mounted on a crossbeam 103 secured tothe upper frame members '70 and 71. The rollers 95 and 96 are carried inyoke members 105 and 106 slidably mounted in the crossbeam 103 andconnected to the pistons of the cylinders 101 and 102.

The shaft 84 (FIGURES 2, 4 and 7) is journaled in bearing blocks 109 and110 mounted in the frame members 70 and 71. A pulley 111 mounted on oneend of the shaft 84 is driven by a belt 112 from another pulley 113mounted on a shaft 114 which is concentric with the bearing sleeves 74and 75 (FIGURE 9).

Mounted on the shaft 114 adjacent the pulley 113 is a gear 116 (FIGURES7 and 9) which meshes with and is driven by a gear 117 (FIGURE 7)secured to the end of the drive shaft 23 which drives the main belt headpulley 36. Accordingly the sealing belt 'head pulleys 85 and 86 aredriven by the same drive as the main belt head pulley 36 and thedimensional relationships between the gears 116 and 117 and pulleys 111and 113 are such that the surface speeds of the rolls are matched to oneanother, or more importantly that the lineal speeds of the reaches ofthe main belt 37 and sealing belts 93 and 94, extending between the headand tail pulleys, are the same.

The shaft 114 (FIGURE 9) is journaled in bearings 118 and 119 mounted inthe bearing sleeve 74. As indicated above, the axis of the shaft 114 isthe same as the axis for the bearing sleeves 74 and 75 about which theupper frame members 70 and 71 pivot between their open and closedpositions. Accordingly pivotal movement of the upper frame members 70and 71 about their axes to lift or lower the sealing belts 93 and 94 maybe done without affecting the drive of the belts through the pulleys 85and 86.

It will be apparent that the torque applied to the main belt head pulley36 should be so limited that the frictional force between the strip Band the belts 37, 93 and 94 will be sufificient to prevent slippage dueto the tension or drag produced by the dynamoelectric machine 26 orother mechanism as such slippage between the strip and the belts mightcause the strip B to be scratched or marred.

In order to prevent this a slip sensing feed-back mechanism is providedto reduce the tension or drag whenever slippage occurs. This mechanism,best shown in FIG- URES 2, 3 and 9, includes a shaft 120 journaledcoaxially with the shaft 114 at one end in a bearing block 121 and atthe other end in a manner to be described below. A bracket 122,pivotally mounted on shaft 120 (FIG- URE 3), carries a strip engagingrubber surfaced roller 124 which is positioned to engage the surface ofthe strip B as it enters the tensioning unit A. The roller 124 issecured to a shaft 125 journaled in the bracket 122. Also secured to theshaft 125 is a gear 126 which meshes with and drives another gear 127keyed to the shaft 120. Accordingly the shaft 120 is driven by roller124 and its speed of rotation is determined by the speed of the strip Bentering the unit A.

Mounted on the shaft 120 at the right-hand end thereof as viewed inFIGURE 9 is a sleeve 130 which is journaled in bearings 131 and 132mounted in the bearing sleeve 75. Keyed to the sleeve 130 is a roller133 which as is best shown in FIGURE 2, is adapted to engage the surfaceof the main belt 37. Accordingly, by virtue of the gearing describedabove, the shaft turns in a direction opposite to that of the sleeve130.

The sleeve carries and drives a bevel gear 134 forming a part of adifferential unit 135, the shaft 120 carrying and driving a coaxialbevel gear 136. So long as the speeds of the bevel gears 134 and 136 arethe same (which is the case when no slippage occurs between the beltsand the strip B) the differential unit 135 will remain stationary. Whenslippage occurs, however, the differential in speed between the bevelgears 134 and 136 will cause rotation of the differential cage 137 whichoperates a current regulator rheostat 138 (FIGURE 9). The rheostat 138adjusts the current of the dynamoelectric machine 26 to reduce thetension or drag induced by the unit to a level at which no slippage willoccur.

In some instances metal strip is rolled with a camber or shape in whichone side of the strip is longer than the other resulting in a strip thatwould form a semicircle if stretched out far enough on a fiat plane.Accordingly it is desirable that some means he provided to guide thestrip through the unit in a manner which will compensate for thiscamber. The necessary adjustment is made by turning the table 11 aboutthe pivot pin 12, using the cylinder 18, to an appropriate angularposition relative to the coil C (see FIGURE 1).

An edge guide 140 (FIGURE 2) is mounted at the exit end of the unit Aand is secured to an external fixed support for keeping the stripaligned with the center line of the unit A. The guide 140 is mounted ona threaded rod 141 so that it-may be adjusted to accommodate differentwidths of strip. I

If desired a detecting device, such as photocell or air stream, may bemounted at the exit end of the unit in a position such that the edge ofthe strip must pass through the device. Whenever the strip deviates fromthe desired path of travel the detecting device feeds a signal to thehydraulic control unit which operates the hydraulic cylinder 18. Thiscauses the cylinder to operate in a manner tending to return thecenterline of the unit A toward the centerline of the strip at the exitend of the unit.

Operation In the operation of the preferred embodiment shown anddescribed herein, after a coil C of metal strip B is positionedforfeeding into the input end of the tensioning apparatus A, the table11 is pivoted on the base 10 to the desired location using the hydrauliccylinder 18. Also the frame members 32 and 33 are adjusted to thedesired angle of tilt using the hydraulic cylinders 34 and 35.

To permit the initial positioning ofthe end of the strip B between themain belt 37 and sealing belts 93 and 94, the upper frame members 70 and71 are pivoted upward away from the main frame members 32 and 33 usingthe hydraulic cylinders 76 and 77 (see dot and dash line position ofmember 71 in FIGURE 1). The end of the strip B is drawn through theapparatus A and placed in position at the exit end thereof for feedinginto further processing equipment such as a temper mill. The edge guide140 is adjusted to the right-hand edge of the strip B as viewed inFIGURE 2.

The sealing belts 93 and 94 are then lowered into sealing engagementwith the top surface of the strip B and the main belt 37, and the vacuumpump 62 is actuated. Following this the dynamoelectric machine 26 isenergized to drive the head pulleys 36 and 86 and thus cause the belts37, 93 and 94 to operate simultaneously and translate the strip B acrossthe span. The belts are kept in firm frictional engagement with thestrip as a result of the vacuum in the grooves 60 in the main belt 37.

Accordingly the strip B may be unwound from the coil C and fed atuniform speed to a temper mill or other processing unit. The unwindingof strip from the coil C will have no effect on the speed ortension ofthe strip as it exits the apparatus A and the strip may be advanced' Anyslippage between the strip B and the belt 37 will be manifested by adifference in speed between the sensing rollers 124 and 133. Thisdifferential results in rotation of the cage 137 of the differentialunit 135 and corresponding adjustment of the rheostat 138. Thus thecurrent or back drag of the dynamoelectric machine 26 will beappropriately increased or decreased to eliminate the slippage.

Although only one embodimentof the invention is illustrated anddescribed it will be understood that variations and modifications may bemade in the form and arrangement of the several parts or elementsthereof without departing from the spirit of the invention.

I claim: v

1. Apparatus for applying tension 'force to a continuous moving strip ofsheet material comprising, a main endless belt driven in a path oftravel including an elongated span parallel to the direction of travelof said strip, the belt portion moving across said span being adapted tofrictionally engage the adjacent surface of said moving strip, said mainbelt having spaced transverse grooves formed in the outer surface andextending intermediate the side edges thereof and having openingstherein spaced longitudinally therearound and located in said grooves,an endless sealing belt means with a moving portion thereof supportedadjacent to and for simultaneous parallel motion with said portion ofsaid main belt as it moves across said span, said sealing belt meansbeing adapted to seal said grooves in said belt portion between an edgeof said strip and the ends of said grooves, evacuating means contiguouswith the portion of said main endless belt extending across said spanand communicating with said openings for evacuating atmosphere from saidgrooves through said openings while said main endless belt is in motion,and means for exerting a force on said main belt for applying a tensionforce on said strip.

2. Apparatus as defined in claim 1 wherein said main endless belt andsaid endless sealing belt means are driven simultaneously by adynamoelectric machine.

3. Apparatus as defined in claim 1 including means for pivoting saidendless sealing belt means into and out of sealing engagement with saidspan of said main endless belt and a strip.

4. Apparatus as defined in claim 1 including two endless sealing belts,one located at each side of said main endless belt, said sealing beltsbeing adapted to seal the opposite ends of said grooves between saidmain endless belt and said strip.

5. Apparatus as defined in claim 1 wherein said evacuating meanscomprises a vacuum box mounted within said main endless belt and adaptedto communicate with the said openings positioned in said span, and meansfor evacuating atmosphere from said vacuum box.

6. Apparatus as defined in claim 1 including means for detectingvariation between the speed of a strip passing through said apparatusand the surface speed of one of said belts in said span, and means foradjusting the force exerted by said belts on said strip to reduce saidvariation.

7. Apparatus as defined in claim 6 wherein said means for detectingvariation between the speed of a strip passing through said apparatusand the surface speed of one of said belts in said span comprises:

a strip engaging roller, a belt engaging roller, and a differential gearunit including:

a first bevel gear operatively connected to said strip engaging roller,and a second bevel gear operatively connected to said belt engagingroller for rotation normally opposite to the rotation of saidfirst-bevel gear and at the same speed when said strip is moving at thesame speed as said belt,

said differential unit being operatively connected to said means foradjusting the force exerted by said belts on said strip whereby saidforce is reduced in response to slippage between said strip and saidmain belt.

8. Apparatus as-defined' in claim 7 wherein said means for exerting aforce on said main belt is a dynamoelectric machine and wherein saidmeans for adjusting said force is a rheostat.

9. Apparatus as defined in claim 1 including means engageable with saidbelts in the reaches thereof opposite to said span for applying atensioning force thereto.

10. Apparatus as defined in claim 9 wherein said means for applying atensioning force to said belts comprises idler rollers movable byhydraulic cylinders in a direction perpendicular to the axes of saidrollers into flexing engagement with said belts.

11. Apparatus as defined in claim 1 including transverse idler rollersengageable with said main belt in said span for supporting said mainbelt during movement across said span.

12. Apparatus for applying tension force to a continuously moving stripof sheet material comprising:

a main belt unit including a head pulley, a tail pulley and an endlessmain belt, said pulleys being adapted to move said belt in a path oftravel including an elongated span parallel to the direction of travelof said strip, the belt portion moving across said span being adapted tofrictionally engage the adjacent surface of said moving strip, said belthaving spaced transverse grooves formed in the outer surface thereof andextending intermediate the side of said belt and-beyond the side edgesof said moving strip, and having openings therein spaced longitudinallytherearound and located in said grooves,

a sealing belt unit including a head pulley, a tail pulley aand anendless sealing belt, said sealing belt unit pulleys being adapted tomove said sealing belt in a path of travel wherein a moving portionthereof is adjacent and in simultaneous parallel motion with saidportion of said main belt moving across said span and adapted to sealsaid grooves in said belt portion between an edge of said strip and aside of said portion of said main belt in said span,

a vacuum box mounted within said main belt and adapted to communicatewith the openings in said main belt which are located in the portion ofsaid main belt moving across said span, means for evacuating-gas fromsaid vacuum box, and

means for driving said belts while frictionally engaging said strip andfor exerting a pulling force on said strip.

13. Apparatus as defined in claim 12 including means for pivoting saidmain belt unit and said sealing belt unit about the axis of said headpulley of said main belt unit to adjust the slope angle of said span.

14. Apparatus as defined in claim 12 including means for pivoting saidmain belt unit and said sealing belt unit about a vertical axis.

References Cited UNITED STATES PATENTS 3,140,030 7/1964 Stewart 226--3,198,517 8/1965 Martin 271-74 3,358,831 12/1967 Cothrell 271-74 X3,389,908 6/1968 Martin 271-74 ALLEN N. KNOWLES, Primary Examiner US.Cl. X.R. 226-

